Burner comprising a fluidic oscillator, for a gas turbine, and a gas turbine comprising at least one such burner

ABSTRACT

A burner having a pre-mixing passage delimited radially outwardly by a wall, a burner lance and a plurality of fuel injectors arranged in the pre-mixing passage, the injectors extending from the burner lance in the direction of the wall and having fuel nozzles. The fuel supply arrangement has at least one fluidic oscillator that has an interaction chamber, an inlet to the interaction chamber connected to a fuel channel of the fuel supply arrangement, a first outlet channel of the interaction chamber extending at least to a first fuel nozzle and a second outlet channel extending at least to a second fuel nozzle, the fluidic oscillator has one feedback line for each outlet channel, one end of the feedback line terminating into the respective outlet channel downstream of the at least one fuel nozzle, and the other end thereof terminating into an inlet region of the interaction chamber.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2015/070355 filed Sep. 7, 2015, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102014218288.3 filed Sep. 12, 2014. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a burner for a gas turbine, having a central burner axis and a premix passage enclosing the burner axis at least in sections. The premix passage therefore has a passage cross-sectional area which extends around the burner axis. The central burner axis is an infinitely long imaginary line. The passage cross-sectional area may, for example, be arranged around the burner axis annularly or as a full circle. In other words, the premix passage may extend coaxially with the burner axis (same rotation axis). The diameter of the ring or full circle may vary along the burner axis section. In particular, the premix passage may be configured at least in sections as a ring space passage (cross section annular), which may merge into a premix passage section which is configured as a full circle in cross section.

The premix passage is bounded radially outward by a wall. During operation, compressor air can flow through the premix passage. It is used to mix fuel and air, a burner lance or burner hub and a number of fuel injectors being arranged in the premix passage. The fuel injectors, which extend from the burner lance/hub in the direction of the wall, are fluidically connected to a fuel feed arrangement at least partially contained by the burner lance/hub, and have fuel nozzles. The fuel injectors may, for example, comprise both fuel nozzles for gaseous fuel and fuel nozzles for oil operation. The same applies for the burner lance/hub, which as an alternative may also be configured without fuel nozzles.

In the context of this invention, the burner lance may also be referred to as a burner hub.

The burner lance may be arranged centrally in the premix passage. The burner lance may extend upstream into the premix passage, so that the passage is bounded radially inward by the burner lance only in sections. The premix passage may, for example, in this case have a fully circular cross-sectional area downstream of the burner lance. The burner lance may, however, also extend essentially to the output of the premix passage.

As an alternative, the premix passage may be bounded radially inward at least in sections by a burner hub arranged centrally in the passage, which has an essentially frustoconically shaped lateral surface and delimits the premix passage radially inward from upstream to an end region of the hub. The premix passage may merge downstream of the hub into a premix region which is fully circular in cross section. Along the hub, the premix passage therefore has an annular passage cross-sectional area, the diameter of which may decrease in the flow direction. In particular, further premix passages may be arranged in the burner hub, or for example a central pilot burner.

In the context of this invention, the premix passage may also be referred to as a premix channel. Fuel is injected into the premix passage through the fuel injectors and can mix as far as the downstream output of the premix passage with a compressor air flow flowing through the premix passage, so that the premix burner provides at its output a fuel/air mixture to be discharged into a combustion chamber. In addition, fuel may also be injected through fuel nozzles arranged directly on the burner lance.

BACKGROUND OF INVENTION

With the burners of species, maximally low-pollution combustion and avoidance of thermoacoustic instabilities during the combustion are sought.

In particular, although premix burners have low pollution emissions during operation, they are however more susceptible to the formation of pressure pulsations.

SUMMARY OF INVENTION

It is an object of the present invention to provide a burner of the type mentioned in the introduction for a gas turbine, with which reduction of pollution emissions or reduction of pressure pulsations is made possible during operation of the burner.

In a burner of the type mentioned in the introduction, the object is achieved according to the invention in that the fuel feed arrangement comprises at least one fluidic oscillator having an interaction chamber, an input of the interaction chamber being connected to a fuel channel of the fuel feed arrangement, and a first output channel of the interaction chamber extending at least to a first fuel nozzle and a second output channel extending at least to a second fuel nozzle, the fluidic oscillator comprising one feedback line per output channel, the feedback line opening with one of its ends into the respective output channel in the region downstream of the at least one fuel nozzle and with the other end into an input region of the interaction chamber.

For example, the at least first and the at least second fuel nozzle, or the first and second groups of fuel nozzles, may be arranged on a common fuel injector and be arranged distributed in the radial direction for maximally homogeneous distribution of the fuel in the premix passage. The at least first fuel nozzle could, for example, also be arranged on a suction side and the at least second fuel nozzle could be arranged on a pressure side of a fuel injector configured in the form of a swirl impeller.

The first and second groups of fuel nozzles may, for example, also be arranged on different fuel injectors. For example in fuel injectors essentially arranged opposite on the burner lance.

Fluidic oscillators have been known for a long time as fluidic control elements which function without expensive valves. For example, these are used to feed air into the boundary layer of carrying surfaces in order to avoid shedding of the boundary layer.

Fluidic oscillators are operated with a pressurized fluid flow applied to their input. This fluid flow is set in oscillation in the interaction chamber, so that the at least one output of the chamber alternately receives the emerging jet. A pulsating fluid flow therefore emerges from the output channels of the fluidic oscillator, the output channels ejecting the fluid alternately. Known from the prior art are fluidic oscillators with feedback lines, which connect an output region of the interaction chamber to an input region of the interaction chamber in order to stabilize the oscillation in the interaction chamber. The feedback lines of the prior art open into the interaction chamber with one of their ends respectively close to an output of the interaction chamber and open into the interaction chamber with their other end upstream of the output close to the input of the interaction chamber. If the respective output receives a fluid flow in the course of the oscillation, this leads to an increased pressure at one end of the feedback line, which is passed on through the line to the input region, into the region at which the flow just bears on a side wall of the interaction chamber. The oscillating flow is therefore inclined to be shed from the side wall. This leads to an oscillation-stabilizing feedback of the pressure conditions between the output and input regions of the interaction chamber.

According to the invention, it is now proposed to make the feedback lines open not into the output region of the interaction chamber, as in the prior art, but respectively into an output channel in a region downstream of an at least one fuel nozzle or fuel nozzle group, to which the output channel extends. According to the invention, this makes it possible for the pressure conditions in the premix passage in the immediate premix passage region before the fuel nozzles also to have an influence on the feedback signal. The output channel may have an end piece, downstream of the fuel nozzle or the fuel nozzle group, into which the feedback channel opens.

If the static pressure in the premix passage in the region of a fuel nozzle group is higher, less fuel flows through the output channel and the dynamic pressure in the output channel is lower. In the inventive configuration of the feedback line, the feedback signal therefore becomes smaller and the fuel will flow for longer in the output channel than with reversed pressure conditions before the fuel nozzles of the output channel in the premix passage. If the static pressure in the premix passage in the region of a fuel nozzle group is lower, on application to the associated output of the interaction chamber more fuel flows through the associated output channel and the dynamic pressure in the output channel is higher. Since the associated feedback line opens into the output channel downstream of the at least one fuel nozzle of the output channel, the pressure in the feedback line opening into the end region of the output channel is higher and the associated fuel jet will be shed more rapidly from the side wall in the input region of the interaction chamber and apply fuel to the next output. The oscillation of the fuel jet in the interaction chamber will therefore apply fuel for longer to the output channel, of which at least one fuel nozzle opens into a region of the premix passage in which a higher pressure prevails. This compensates for the effect that less fuel generally emerges from fuel nozzles that open into a region of higher passage pressure, and more fuel is injected into regions of low pressure. By this compensation, according to the invention a more homogeneous fuel concentration can be generated in the premix passage. The injection of the fuel through the at least two fuel nozzle groups, or fuel nozzles, connected to the fluidic oscillator is therefore regulated automatically, without an additional control device being required therefore. The resulting more homogeneous distribution of the fuel concentration in the premix passage leads to reduced pollution emissions. Because of the fuel injection fluctuating as a function of time and position, good mixing of fuel ejected by the fuel nozzle groups with the compressor air flowing past is furthermore achieved. According to the invention, because of the fluctuating fuel injection by the fluidic oscillator, broadening of the dwell time profile of the burner is also achieved, so that an interaction of the burner with the flame and creation of thermoacoustic oscillations are reduced.

For explanation of the terms thermoacoustic oscillation and dwell time, it should be noted that an interaction of acoustic oscillations and variations in the release of heat can occur in a combustion chamber. These may exacerbate one another when frequencies are involved which coincide with so-called natural modes of the gas turbine. These natural modes are dependent on the size and design of the respective gas turbine. Such thermoacoustic oscillations may cause serious damage to the components during operation of the gas turbine and force shutdown of the system.

In order to avoid the excitation of thermoacoustic oscillations, the dwell time profile of the burner set up during operation may be as wide as possible, the dwell time being the time taken by a fluid emerging from the fuel nozzle to reach the flame.

Because of the fuel jet pulsating as a function of both time and position at the exit of the nozzles, the fuel nozzles, or fuel nozzle groups, of the burner which are supplied with fuel by the fluidic oscillator cause a fluctuation of the fuel concentration profile in the compressor air flowing past, which in turn improves the thermoacoustic stability because of a broadened dwell time profile of the burner—for example in comparison with burners having conventional pressure-swirl or full-jet nozzles. A frequency of the pulsating injection of the fuel may, for example, be adjusted by the size of the interaction chamber. The burner may comprise a plurality of fluidic oscillators which each supply at least two output channels, respectively having at least one fuel nozzle or group of fuel nozzles, with fuel.

Different types of fluidic oscillators are known, which differ in their construction. The invention is not restricted to a special type of these fluidic oscillators. A common feature of all these types is that they have an interaction chamber which a pressurized fluid jet enters through an input. The jet is applied periodically to different side walls or side-wall regions of the interaction chamber, so that an interaction of the jet with the side walls of the chamber may be referred to, and oscillation of the jet being created so that the jet flows through the chamber periodically on different paths and in the output region consequently leaves it periodically through different outputs of the interaction chamber, or leaves a central output of the interaction chamber in different directions. The jet is therefore periodically applied at least to two opposite side-wall regions, and shed again, which is induced by retardation of the flow.

The functionality of fluidic oscillators is prior art, for which reason the fluidic oscillators are explained only briefly here. Furthermore, a few types of fluidic oscillators are represented in the drawing. The invention is independent of the type of fluidic oscillator used. The invention is advantageously based on a fluidic oscillator which leads to creation of the oscillation of the incoming jet because of diverging side walls in the input region of the interaction chamber. In particular, the invention is advantageously based on an essentially rotationally symmetrical configuration of the interaction chamber, with the input arranged around the rotation axis at one end of the chamber and the output region with the at least one output arranged opposite. In order to create the oscillation, the interaction chamber widens in this type of interaction chamber in the manner of a diffuser in the direction of the output region, at least in the input region of the chamber. The functionality of the feedback lines has already been explained above.

Advantageous configurations of the invention are specified in the following description and the dependent claims, the features of which may be used individually and in any desired combination with one another.

Provision may advantageously be made that the first output channel extends to a first group of fuel nozzles and the second output channel extends to a second group of fuel nozzles, the feedback line respectively opening into the output channel in a region downstream of the respective group of fuel nozzles.

The first and second groups of fuel nozzles, or the first and second fuel nozzles, may for example be arranged in a common fuel injector. The fuel injector may, for example, be a swirl impeller of a swirl generator. Since different pressures prevail in the premix passage on the suction and pressure sides of the impeller, the first fuel nozzle or the first group of fuel nozzles may be arranged on the suction side, and the second fuel nozzle or fuel nozzle group may be arranged on the pressure side of the swirl impeller. According to the invention, in this way an approximately equal amount of fuel can be injected on both sides of the impeller.

It may also be regarded as advantageous for the feedback line to connect to the output channel downstream of the at least one fuel nozzle.

The output channel and the feedback line may in this case have different diameters.

It may also be regarded as advantageous for the at least first fuel nozzle and the at least second fuel nozzle to be arranged in different fuel injectors.

In particular, it may be regarded as advantageous for the two fuel injectors to be essentially arranged opposite one another on the burner lance.

In this way, the fuel concentration in the premix passage may be similar to one another in the at least two opposite regions, despite different pressure conditions in the regions.

It may also be regarded as advantageous for the at least two fuel nozzles, or at least two fuel nozzle groups, to be arranged in a common fuel injector and differ by their radial arrangement in the premix passage, so that the fuel concentration in the radial direction can be homogenized despite different pressure conditions in the region of the premix passage close to the burner lance and in the region of the premix passage remote from the burner lance.

The fluidic oscillator may be arranged in the burner hub or in the fuel injector.

Advantageously, provision may furthermore be made for the burner to comprise more than two groups of fuel nozzles, connected to the fluidic oscillator in this way, in different fuel injectors.

This allows homogenization of the fuel concentration in the premix passage downstream of the different fuel injectors.

According to another advantageous configuration of the invention, the different fuel injectors may be arranged circumferentially on the burner lance, and the associated output channels may be arranged circumferentially on the interaction chamber.

It may also be regarded as advantageous for the at least one fuel injector to comprise a base body, on which the fuel nozzles contained by the fuel injector are arranged, the base body being in particular a swirl impeller of a swirl generator.

Advantageously, provision may furthermore be made for the interaction chamber to comprise the input at one of its ends and an output region at an opposite end, and to be bounded by side walls or side-wall regions which extend from the input of the chamber to the output region comprising the outputs, at least two oppositely arranged side walls or side-wall regions diverging in the direction of the output, at least in the input region.

The oscillation of a fuel jet entering under pressure into the interaction chamber through the input is created according to this configuration of the invention by alternating application of the jet to the divergently configured side-wall regions. The creation of the oscillation in the interaction chamber according to the invention is based on the flow retardation induced in the input region by the diverging side walls/side-wall regions.

It may also be regarded as advantageous for at least two oppositely arranged side walls to diverge in the input region of the interaction chamber in the direction of the output at an angle of more than 7.5 degrees with respect to an influx direction of the input of the interaction chamber.

Aperture angles of the interaction chamber, which are suitable for the creation of an oscillation, are known from the prior art. An angle of at least 7.5 degrees with respect to the influx direction has been found to be particularly advantageous.

Advantageously, provision may be made for the interaction chamber to be essentially configured rotationally symmetrically, the interaction chamber widening at least in the input region in the manner of a diffuser in the direction of the output.

By the rotationally symmetrical structure of the fluidic oscillator, circumferential application of fuel to the output channels that begin in the output region of the interaction chamber is obtained.

The fluidic oscillator may, for example, be arranged centrally in the burner lance and supply fuel injectors arranged rotationally circumferentially on the burner lance with fuel, respectively with at least one output channel of the fluidic oscillator extending respectively to a group of fuel nozzles of a fuel injector. The circumferential fuel injectors may together comprise two fuel stages. A separate fluidic oscillator may be provided for each stage.

It is another object of the invention to provide a burner arrangement having a number of burners, —main burners being arranged in one or more circles arranged concentrically with one another, with which a reduction of pollution emissions or a reduction of pressure pulsations during operation of the burner arrangement is made possible.

To this end, at least one burner is configured as claimed.

The burner may, for example, be a centrally arranged pilot burner of the burner arrangement. According to another exemplary embodiment, in addition or as an alternative, the main burner of the burner arrangement may also be configured as claimed.

The burner according to the invention, or the burner arrangement according to the invention, allows particularly stable combustion, in particular also during partial load operation.

It is another object of the invention to provide a combustion chamber for a gas turbine and a gas turbine, with which a reduction of pollution emissions or a reduction of pressure pulsations in the combustion chamber during operation is made possible.

To this end, the combustion chamber comprises at least one burner as claimed, and the gas turbine comprises at least one combustion chamber as claimed.

Further expedient configurations and advantages of the invention are the subject of the description of exemplary embodiments of the invention with reference to the figures of the drawing, references which are the same denoting components which have the same effect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a gas turbine of the prior art in a longitudinal section,

FIGS. 2, 3 schematically show two types of fluidic oscillator according to the prior art in a longitudinal section,

FIG. 4 schematically shows a detail of a combustion chamber 10 of the prior art in a longitudinal section,

FIG. 5 schematically shows a main burner of the burner arrangement represented in FIG. 4 in a longitudinal section,

FIG. 6 schematically shows a burner according to the invention according to a first exemplary embodiment of the invention in a longitudinal section, and

FIG. 7 schematically shows a burner according to the invention according to a second exemplary embodiment of the invention in a longitudinal section.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a sectional view of a gas turbine 1 according to the prior art in a schematically simplified representation. The gas turbine 1 internally comprises a rotor 3 which is mounted so as to rotate about a rotation axis 2, has a shaft 4 is also referred to as the turbine rotor. Successively along the rotor 3, there are an intake manifold 6, a compressor 8, a combustion system 9 having a number of combustion chambers 10, each of which comprises a burner arrangement having burners 11, a fuel supply system (not represented) for the burners and a housing 12, a turbine 14 and an exhaust manifold 15. The combustion chamber 10 may, for example, be a ring combustion chamber. The gas turbine could however also comprise tube combustion chambers, which are for example arranged annularly at the turbine entry.

The combustion system 9 communicates with an e.g. annular hot-gas channel. There, a plurality of turbine stages connected in series form the turbine 14. Each turbine stage is formed from blade rings. As seen in the flow direction of a working medium, a row formed by the guide vanes 17 is followed in the hot channel by a row formed by rotor blades 18. The guide vanes 17 are in this case fastened on an inner housing of a stator 19, while the rotor blades 18 of a row are fitted on the rotor 3, for example by means of a turbine disk. Coupled to the rotor 3, there is for example a generator (not represented).

During operation of the gas turbine, air is taken in by the compressor 8 through the intake manifold 6 and compressed. The compressor air L″ provided at the end of the compressor 8 on the turbine side is guided along a burner plenum 7 to the combustion system 9, where it is guided into the burners 11 in the region of the burner arrangement and mixed with fuel in them and/or enriched with fuel in the exit region of the burner 11. Fuel supply systems in this case supply the burners with fuel. The mixture, i.e. the compressor air and the fuel, are introduced into the combustion chamber 10 by the burners 11 and burn while forming a hot working-gas flow in a combustion zone inside the combustion-chamber housing 12 of the combustion chamber. From there, the working-gas flow flows along the hot-gas channel past the guide vanes 17 and the rotor blades 18. At the rotor blades 18, the working-gas flow expands by imparting momentum, so that the rotor blades 18 drive the rotor 3 and the generator (not represented) coupled to it.

FIG. 2 shows a fluidic oscillator of a first type according to the prior art in longitudinal section.

The oscillator 24 a comprises an interaction chamber 26 having an input 28 with an input region 30 and an oppositely arranged output region 32 with a first output 34 and a second output 36. A relatively thin feedback line 38, which connects the input region to the output region, is arranged at each output.

The side-wall regions 40 diverge in the direction of the output, so that the interaction chamber 26 has a triangular longitudinal section. The oscillator 24 a is not constructed rotationally symmetrically, but has a constant longitudinal section perpendicularly to the plane of the drawing.

FIG. 3 shows a fluidic oscillator 24 b of a second type according to the prior art in longitudinal section. The oscillator 24 b is likewise not constructed rotationally symmetrically, but has a constant longitudinal section perpendicularly to the plane of the drawing. The input 28 is arranged inside a guide means 42 centrally in the interaction chamber 26, so that a jet entering under pressure is guided frontally onto the opposite side wall 44. The jet alternately flows leftward and rightward at the guide means in the direction of the output region 32, while alternately applying the fluid to the outputs 34 and 36, so that the jet emerges from the chamber alternately through one output and the other, with a frequency which is determined by the size of the interaction chamber 26.

FIG. 4 schematically shows a detail of a combustion chamber 10 of the prior art with a burner arrangement 48 at a head end of the combustion chamber. The combustion chamber comprises a combustion-chamber wall having a flame tube 50 comprising a combustion zone, and having a transition piece 52 which follows on from the flame tube and extends to a turbine entry of the gas turbine. In order to dampen thermoacoustic oscillations which occur during operation, resonators 54 are arranged at the level of the flame on the combustion-chamber wall. The burner arrangement 48 comprises a central pilot burner 56 having a central pilot-burner lance 58 and a pilot-burner premix passage 60. The pilot burner 56 comprises a pilot cone 62 widening conically in the flow direction. Main burners 64 are arranged circularly around the central pilot burner. The main burners 64 each have a burner axis 66 and a premix passage 68 arranged concentrically with the burner axis; the premix passage 68 is bounded radially outward by a wall 70, compressor air L″ can flow through it during operation, and it is used to mix fuel and air L″, the premix passage 68 containing a central burner lance 72 and a number of fuel injectors, which extend from the burner lance in the direction of the wall 70, are connected fluidically to a fuel feed arrangement which the burner lance 72 comprises, and have fuel nozzles. The fuel injectors are configured as swirl impellers of a swirl generator 74, fuel nozzles being arranged on the swirl impellers.

FIG. 5 shows a main burner 64 of the burner arrangement of FIG. 4 schematically in longitudinal section. The burner 64 has a central burner axis 66 and a premix passage 68 enclosing the burner axis at least in sections; the premix passage is bounded radially outward by a wall 70, compressor air L″ can flow through it during operation, and it is used to mix fuel and air. The premix passage 68 contains a central burner lance 72 and a number of fuel injectors 79. The fuel injectors 79 each comprise a base body 71, which is arranged in the premix passage and is configured as swirl impellers 76 of a swirl generator 74. The fuel injectors 79 comprise fuel nozzles 80, which open into the premix passage 68 on the surface of the swirl impellers 76. The fuel nozzles 80 are fluidically connected to a fuel feed arrangement 73 in order to be supplied with fuel. The fuel feed arrangement 73 comprises a fuel channel 82 extending in the burner lance, and fuel feed channels 78 which extend into the swirl impellers 76 as far as the respective fuel nozzles 80.

FIG. 6 schematically shows a burner 84 according to the invention in longitudinal section according to a first exemplary embodiment of the invention. In contrast to the burner 64 of the prior art as represented in FIG. 5, the fuel feed arrangement 73 has at least one fluidic oscillator 85 with an interaction chamber 26, an input 28 of the interaction chamber being connected to the fuel channel 82 of the fuel feed arrangement 73. Opposite the input region 30 with input 28, the interaction chamber 26 has an output region 32 with two outputs 34 and 36. A first output channel 86 extends from the output 34 to a first group of fuel nozzles 80 a in a first fuel injector 79 a. A second output channel 88 extends from the output 36 to a second group of fuel nozzles 80 b in a fuel injector 79 b arranged opposite, the fluidic oscillator 85 comprising a feedback line 38 a, 38 b for each output channel, the feedback line 38 a, 38 b opening with one of its ends into the respective output channel 86, 88 downstream of the fuel nozzles 80 a, 80 b which the output channel comprises, and with the other end into the input region 30 of the interaction chamber 26.

If the input 28 of the fluidic oscillator 85 is supplied with a pressurized fuel flow by means of the fuel channel 82 during operation of the burner, the fuel flow in the interaction chamber 26 will be excited into oscillating application on the side walls of the chamber because of the diverging side walls in the input region 30, and will therefore supply the outputs 34 and 36 alternately with fuel. The fuel flows to the respective fuel nozzle groups through the output channels 86, 88, so that a pulsating fuel flow is injected from the latter into the premix passage 68. The fuel nozzles may, for example, be full-jet nozzles or pressure-swirl nozzles. The feedback line 38 a is connected downstream of the fuel nozzles 80 a to the output channel 86 and couples the pressure prevailing at the end of the output channel back to the input region 30 of the interaction chamber. The pressure prevailing at the end of the output channel is in this case influenced by the pressure in the premix passage immediately before the fuel nozzles 80 a, so that when there is a high pressure in this region the fuel supply is switched over to the second group of fuel nozzles 80 b more slowly than would be the case with a lower pressure. The group of fuel nozzles will therefore inject fuel for a longer time into the compressor air flow flowing past, before which the pressure in the premix passage is higher, so that a more uniform fuel concentration is set up at the output of the burner even when there are different pressure conditions on the two sides of the burner lance 72. This counteracts creation of pressure pulsations and reduces the production of pollution emissions.

FIG. 7 schematically shows a burner 90 according to the invention according to a second exemplary embodiment of the invention. The burner 90 has a central burner axis 66, a premix passage 92, which is in the form of a ring space, extends concentrically with the burner axis 66, and is bounded outward by a wall 70, and a centrally arranged burner hub 94. Arranged in the premix passage 92, there is a diagonal grid 96 which imparts a swirl to the compressor air L″ flowing in the premix passage. The diagonal grid consists of a number of fuel injectors 98, which are arranged circumferentially around the hub and whose base bodies arranged in the premix passage impart a velocity component pointing in the circumferential direction of the passage to the compressor air L″ flowing past. Extending in the burner hub 94, there is at least one fuel channel 82, which may be formed circumferentially in the cone of the burner hub and via which fuel nozzles 80, 80 a, 80 b of the fuel injectors 98 are supplied with fuel. According to the exemplary embodiment, at least two output channels of a fluidic oscillator (not represented) extend in at least one fuel injector 100. The fluidic oscillator is fluidically arranged between the fuel channel 82 and at least a first and a second group of fuel nozzles, which are supplied with fuel in the fuel injector 100 via a first and a second output channel (not represented) of the fluidic oscillator. The fuel nozzles of the first group are denoted by 80 a and are arranged on the hub side on the fuel injector, the fuel nozzles of the second group being denoted by 80 b and injecting fuel into the premix passage radially further outward on the fuel injector. The exemplary embodiment makes it possible to obtain a fuel concentration which is homogeneous in the radial direction at the output of the premix passage even in the event of different flow speeds or pressure conditions in the outer region, i.e. the region on the hub side, of the premix passage. 

1. A burner comprising: a central burner axis and a premix passage enclosing the burner axis at least in sections, the premix passage being bounded radially outward by a wall, being capable of being flowed through during operation by compressor air, and being used to mix fuel and air, there being arranged in the premix passage a burner lance or burner hub and a number of fuel injectors which extend from the burner lance or burner hub in the direction of the wall and comprise fuel nozzles fluidically connected to a fuel feed arrangement at least partially contained by the burner lance or burner hub, wherein the fuel feed arrangement comprises at least one fluidic oscillator having an interaction chamber, an input of the interaction chamber being connected to a fuel channel of the fuel feed arrangement, and a first output channel of the interaction chamber extending at least to a first fuel nozzle and a second output channel extending at least to a second fuel nozzle, the fluidic oscillator comprising one feedback line per output channel, the feedback line opening with one of its ends into the respective output channel in the region downstream of the at least one fuel nozzle and with the other end into an input region of the interaction chamber.
 2. The burner as claimed in claim 1, wherein the first output channel extends to a first group of fuel nozzles and the second output channel extends to a second group of fuel nozzles, the feedback line respectively opening into the respective output channel in a region downstream of the respective group of fuel nozzles.
 3. The burner as claimed in claim 1, wherein the feedback line connects to the output channel downstream of the at least one fuel nozzle.
 4. The burner as claimed in claim 1, wherein the at least first fuel nozzle and the at least second fuel nozzle are arranged in different fuel injectors.
 5. The burner as claimed in claim 1, wherein the two fuel injectors are essentially arranged opposite one another on the burner lance.
 6. The burner as claimed in claim 4, wherein the burner comprises more than two groups of fuel nozzles, connected to the fluidic oscillator in this way, in different fuel injectors.
 7. The burner as claimed in claim 6, wherein the different fuel injectors are arranged circumferentially on the burner lance, and the associated output channels are arranged circumferentially on the interaction chamber.
 8. The burner as claimed in claim 1, wherein the at least one fuel injector comprises a base body, on which the fuel nozzles contained by the fuel injector are arranged.
 9. The burner as claimed in claim 1, wherein the interaction chamber comprises the input at one of its ends and an output region at an opposite end, and is bounded by side walls or side-wall regions which extend from the input of the chamber to the output region comprising the outputs, at least two oppositely arranged side walls or side-wall regions diverging in the direction of the output region, at least in the input region.
 10. The burner as claimed in claim 1, wherein at least two oppositely arranged side-wall regions diverge in the input region of the interaction chamber in the direction of the output region at an angle of more than 7.5 degrees with respect to an influx direction of the input of the interaction chamber.
 11. The burner as claimed in claim 1, wherein the interaction chamber is essentially configured rotationally symmetrically, the interaction chamber widening at least in the input region in the manner of a diffuser in the direction of the output region.
 12. A burner arrangement comprising: a number of burners, with main burners being arranged in one or more circles arranged concentrically with one another, wherein at least one burner is configured as claimed in claim
 1. 13. A combustion chamber for a gas turbine, comprising: at least one burner as claimed in claim
 1. 14. A gas turbine comprising: at least one combustion chamber, wherein the combustion chamber is configured as claimed in claim
 13. 15. The burner as claimed in claim 8, wherein the base body comprises a swirl impeller of a swirl generator. 